Latex paints and resinous dispersion coatings ("resinous materials") generally are comprised of polymeric resins such as acrylics, styrene-butadienes, polyvinyl acetates and acrylates; plasticizers; surfactants; inorganic fillers such as aluminum compounds, silica and transition metals; and colorants such as titanium dioxide, cobalt compounds, and chromium compounds.
Manufactures and industrial consumers of resinous materials typically utilize storage tanks and application equipment with large liquid storage capacity to store and handle resinous materials. When such tanks and equipment are shut down for maintenance or when the resinous material formulation is changed, it is frequently necessary to clean the dried and agglomerated resinous material from tank and equipment surfaces. Industrial equipment for handling resinous material, including all the associated piping, is often capable of holding hundreds of gallons of resinous materials and is not easily disassembled for cleaning. Such equipment must be "cleaned-in-place" because disassembly for cleaning is difficult or impossible. Equipment which must be cleaned-in-place is typically designed with cleaning systems which include agitation means to contact the equipment internal surfaces with cleaners to remove resinous material without requiring substantial equipment disassembly. As used herein, the term "agitation" is defined as any action to circulate and/or recycle the invention cleaning composition in contact with the substrate to be cleaned. The term "agitation" includes, but is not limited to, pumping, spraying, foaming, shaking and vibrating. The systems which are designed to clean equipment without substantial disassembly are called clean-in-place (CIP) systems. In order for CIP systems to be effective, resinous material cleaners must not only soften dried and /or agglomerated resinous material deposits, the cleaner must also cause the deposits to be easily removed from the substrate with minimal agitation.
It is well known in industry that volatile solvents such as acetone and methanol, and chlorinated solvents such as methylene chloride and carbon tetrachloride, are effective as resinous material cleaners for CIP operations. However, volatile organic solvents and chlorinated organic solvents are increasingly unacceptable for many operations due to flammability and environmental concerns.
Thus a need exists for a resinous material cleaner which is effective for use in CIP operations and which does not have the problems associated with volatile organic and chlorinated hydrocarbon solvents.
Accordingly, it is an object of this invention to provide an aqueous cleaning composition effective for removing resinous materials from equipment surfaces which must be cleaned-in-place.